This book is a complete End to End reference guide for SQL Server 2008 Integration Services. This book starts with a very good basic introduction to the all the tools and tasks available in SSIS. There is very detailed explanation of the basic tasks which are more frequently used such as Script Task, Execute SQL task and Send Email. Good description on the containers which we need for looping through a set of tasks which is more common in any development.
During development, the most common thing we would like to /need to do is making the package dynamic. There is a good chapter to explain how to use expressions effectively to have runtime configurations in the package. Other very good chapters to refer are Scripting in SSIS which explains the scripting capabilities using .NET and C#. The chapter, Accessing Heterogeneous Data, which explains how to access various heterogeneous data sources such as Excel, Flat File, XML, ADO.NET, OLE DB and many with examples.
The later chapters explain more about optimizing SSIS packages, error handling and event handling, Migrating DTS Packages. The chapter which explains accessing external applications is good but needs more examples to highlight the capability of SSIS accessing various external applications.
Too many pages, yes, the book has. But to refer SSIS with good samples and Screenshots (The screenshots are helpful in few instances), I wouldn't mind reading these many pages.
For any new developer, who wants to know from the basics and a complete End to End flow of SSIS before start using SQL Server 2008 Integration for ETL development, this is one good reference book I would recommend.